Acoustical tiles are specially designed systems that are intended to improve acoustics by absorbing sound or reducing sound transmission in an indoor space, such as a room, hallway or conference hall, or the like. Although there are numerous types of acoustical tiles, a common variety of acoustical tile is generally composed of mineral wool fibers, fillers, colorants and a binder, as disclosed, for example, in U.S. Pat. No. 1,769,519. These materials, in addition to a variety of others, can be employed to provide acoustical tiles with desirable acoustical properties and other properties, such as color and appearance.
Although, as discussed above, there are a variety of commercially available acoustical tile products, there are currently no formaldehyde-free acoustical ceiling products comprised of mineral wool fiber on the market today. A number of products classified as low volatile organic chemical (VOC) emitters are available, however, all of these products emit detectable levels of formaldehyde due to the presence of various formaldehyde emitting components that are employed in these tiles. The inventors have found that certain polymeric binders used in surface treatments and back coatings inherently contain, release, emit or generate formaldehyde. In addition, additives such as wet-state preservatives or biocides included in the surface treatments and back coatings can also release, emit or generate detectable and quantifiable levels of formaldehyde. Thus, even though formaldehyde may not be a component of a polymeric binder or a biocide as used in acoustical tile, the tile may still release, emit or generate formaldehyde for a number of reasons, including, for example, degradation of the polymeric binder and/or biocide. Although formaldehyde emissions that are generated during heat exposure in the manufacturing process may be exhausted into the stacks or thermal oxidizers, the resulting product will still contain residual formaldehyde, which is emitted upon installation. A reduction in formaldehyde emissions, or elimination of such emissions, will provide improved indoor air quality in those locations where acoustical tiles are installed, such as schools, healthcare facilities, or office buildings.
This invention provides an acoustical tile and a process of manufacturing an acoustical tile. These and other advantages of the present invention will be apparent to those skilled in the art in view of the detailed description of this invention.